docs: def saveWeights(sim):
      ''' Save the weights for each plastic synapse '''
      with open(sim.weightsfilename,'w') as fid:
          for weightdata in sim.allWeights:
              fid.write('%0.0f' % weightdata[0]) # Time
              for i in range(1,len(weightdata)): fid.write('\t%0.8f' % weightdata[i])
              fid.write('\n')
      print(('Saved weights as %s' % sim.weightsfilename))